An electromechanical brake (EMB) is an electric brake device that presses a piston by converting rotational force of a drive motor into rectilinear motion using a screw/nut mechanism without using hydraulic pressure. In the EMB, when a screw gear is rotated by a gear that increases rotational force of the drive motor, a spindle converts rotational motion of the screw gear into rectilinear motion so as to press the piston, and the pressed piston presses a pad against a wheel disc, such that a caliper body is moved by reaction force generated by piston force.
Recently, a hybrid EMB system, which is used in combination with a hydraulic device in the EMB, has been suggested. In the EMB, a separate abrasion compensation device needs to be provided for compensating for abrasion of a brake pad, and a separate motor and multiple peripheral components are required to compensate for abrasion, and as a result, there is a problem in that a volume and a weight of the EMB are increased.
However, in the case of the aforementioned EMB system used in combination with a hydraulic device, a function of compensating for abrasion may be performed using a more simple structure and configuration, thereby reducing a weight and a volume of the EMB. Further, at the time of an emergency, braking force may be generated by a mechanical mechanism, thereby ensuring sufficient brake safety.
The EMB system used in combination with a hydraulic device is disclosed in Korean Patent No. 10-1138510. However, there is a problem in that it is difficult to add a parking brake function to the EMB system disclosed in the patent.